Rock drill



Patented Jan. 9, 1934 RGCK DRILL Albert Feucht, Cleveland, Ohio, assigner to The Cleveland Rock Drill Company, Cleveland, (Ehio, a corporation of Ohio Application September 7, 1932. Serial No. 631,980

2 Claims.

This invention relates broadly to rock drills but more particularly to valvular mechanism therefor.

Teretofore it has been the practice in designrock drills of the valve or valveless type to ..-it the pressure fluid into the front end of the 'nder somewhat prior to the termination oi a valve chamber 24 having a valve 25 reciprocably mounted therein. The bottom of the bore 20 within the valve chamber 24, is formed with an annular groove 25 in constant communication with the atmosphere through a restricted port 27. The valve cap 23 is manufactured with a centrally disposed enlarged bore 23 within which the the working stroke oi the piston, thus creating stem 13 is reciprocably guided. Formed Within a cushion tending to retard the velocity of the the bore 23, there is an annular groove 29 which piston during its working stroke, and consequently interiering with the eliiciency of the machine.

It is an object of this invention to produce a rock drill with means aiiording an unrestricted ilow of the pressure into the iront end of the cylinder subsequent to the impact of the piston upon the 'workiniT implement, thus increasing the eliciency of the machine.

Other objects of this invention will be apparent from the following detailed description wherein similar characters of reference designate corresponding parts and wherein:

Fig. 1 is a longitudinal sectional View of a partion of a rock drill embodying the invention.

Fig. 2 and Fig. 3 are enlarged sectional views illustrating the valve and piston in diierent positions.

The embodiment of the invention chosen for the purpose ci illustration comprises a cylinder ed with a piston chamber ll. Reciprounted within this chamber, there is a p provided with an integral stem 13. The ste-ni adjacent the head is formed of a re'- stricted diameter constituting a neck 14. Secured in pressed fit engagement within the front end of the piston Chamber l1, there is a tappet bushing 15. The tappet bushing is properly machined to slidably receive a tappet 16 with one end thereof extending into the iront end of the piston chamber 11 and capable to receive the impact of the piston l2. VThe other end of the tappet 1S is capable of engagement with the end ci a drill steel 17 to transmit to the latter the impact of the piston l2. rIhis drill steel is slidably mounted within a front housing 18, which may be secured to the cylinder by any suitable means.

Secured within the rear end of the piston chamber 11 in iiuid tight engagement with the wall thereof, there is a valve block 19. This valve block is formed with a plurality of differential bores 20, 21, and 22. The bores 20 and 22 are adequately machined to receive, in fluid tight engagement therein, a valve cap 23. Intermediate the valve cap 23 and the valve block 19, there is is capable of communication with the front end oi the piston chamber 11 through a plurality of passages 30, 3l, and 32. 'I'he passage 30 may be opened or closed by the Valve 25 as will be eX- plained hereafter. Leading from the valve cap bore 28 into the valve chamber 24, in constant spaced relation with the valve 25, there is a kick port 33; and leading from the valve chamber 24 to the atmosphere, there is a restricted vent hole 34.

The machine is terminated by a backhead 35 having rotatably therein a throttle valve 36, from which pressure fluid may be admitted into an enlarged reservoir 37 and valve cap bore 28 through the passages 38 and 39. Leading from the reservoir 37 into the valve cap bore 28, there is a plurality of passages 4i) and 4.1.v It Will be observed that the passages 41 are adapted to be closed by the piston stem 13 and capable of communication with the rear end of the piston chamber 11, through the space formed around the piston neck 14 and valve cap bore 28. Adjacent to the front end of the valve 25, the bottom of the bore 21 is maintained in constant communication with one of the bores 41 through a restricted opening 42. Leading from the piston chamber l1 to the atmosphere, there is an enlarged exhaust passage 43.

Assuming the valve 25 and piston 12 to be positioned as illustrated in Fig. 3, pressure iiuid admitted into the reservoir 37 will flow therefrom through the passages 40 and 41, and around the neck 14 into the rear end of the piston chamber 1l and act upon the rear face of the piston 12 to drive the latter forwardly. The piston stem 13, reciprocably mounted Within the valve cap bore 28, is constantly subjected to the action of the pressure fluid from the reservoir 37. The pressureexerted on that stem cooperates with the pressure exerted on the piston 12 to drive the same forwardly. During the forward stroke of the piston, the stein 13 will cover the passages 41, thus shutting oli the admission of the pressurek iuid into the rear end of the piston chamber. However, the piston 12 is continuing its forward stroke by the expansion oi the pressure fluid Within the rear end of the piston chamber 11 and also by the pressure acting on the rear end of the stem 13. The valve 25 is maintained in its rearward position by the pressure admitted to the front end of the valve, hereafter denoted as restricted holding area, from one of the passages 41 through the restricted opening 42, and to the valve enlarged actuating area 45, through the ports 27. Toward the end of its forward stroke, the piston 12 will uncover the exhaust passage 43, allowing the pressure fluid from the rear end of the piston chamber 11 to escape to atmosphere. Subsequently the end of the stem 13 will uncover the kick port 33, and allow pressure fluid into the valve chamber 24 to act upon the valve restricted actuating area 44 and kick the valve 25 in the forward position as illustrated in Fig. 2, the front of the valve chamber 24 being constantly vented to the atmosphere through the restricted port 27. The passages 30 being uncovered by Jthe valve 25, pressure fluid from the valve cap groove 29, will ow through the passages 30, ,31, and 32. Simultaneously the piston 12 striking the tappet 16 will cover the passages 32, thus detaining the admission of the pressure fluid into the front end of the piston chamber 11. Due to the rebound of the piston upon the tappet 16 together with the com-pression of the atmosphere into the front end of the piston chamber 11, the piston 12 will be driven rearwardly sufliciently to uncover the passages 32 and admit pressure into the front end of the piston Achamber 11 to return the piston. By providing a valve controlled by the stem of the piston, pressure fluid is never admitted into the front end of the piston chamber 11, previous to the engagement of the piston 12 with the tappet 16. Thus the piston is free to deliver its blows to the tappet without being retarded by lthe action of the pressure fluid, increasing thereby the efficiency of the machine. The valve 25 is maintained in its forward position by the action of the pressure fluid upon the rear end of the valve, which will hereafter be denoted as enlarged holding area.

During the rear stroke of the piston, the kick port 33 will be covered by the stem 13, thus shutting olf the admission of pressure fluid into the chamber 24, while the pressure remaining therein is vented to the atmosphere through the vent hole 34. Continuing its rearwardL stroke, the piston stem 13 will cover the groove 29, thereby shutting off the admission of the pressure fluid into the front end of the piston chamber 11 previous to the communication of that end of the piston chamber with the exhaust passage 43. With the groove 29 covered by the stem 13, the pressure fluid is prevented from acting upon the enlarged holding area of the valve, thus allowing the latter to trip rearwardly by the pressure acting upon the valve restricted area through the restricted opening 42. The piston reaching the end of its-rearward `str oke will afford the communication of its neck 14 with the passages 41, thus admitting pressure fluid into the rear end of the piston chamber 11 to drive the piston 12 forwardly as previously explained.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or conning and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

l. A rock drill comprising a cylinder formed with a piston chamber, a piston reciprocable therein, said piston having a stern extending therefrom, a neck within said stem, a valve block wit-hin said cylinder, a liner detachably secured within said block through which the stem of said piston is slidably guided, an annular valve chamber formed between said block and liner having a valve reciprocable therein, passages within said val-ve lblock and liner controlled by the neck of said stem for admitting pressure fluid into one end of said piston chamber to actuate said piston in one direction, passages leading from the interior Aof said liner and controlled by s aid valve for admitting pressure fluid into the other end of said piston chamber to actuate said piston in the other direction, said valve comprising a restricted pressure area constantly subjected to the action of the pressure fluid for shifting and holding said valve in one position, a shifting area subjected to the pressure fluid for shifting said valve in the other position, and an enlarged holding area intermittently subjected to the action of the pressure fluid for holding said valve into said last mentioned position, the pressure huid admitted to said shifting area being controlled solely by the end of said piston stem within said liner.

2. A rock drill comprising a cylinder formed with Aa piston chamber, a piston reciprocable therein, said piston having a stem extending therefrom, a neck within said stem, a valve block within said cylinder, a liner detachably secured within said block through which the stem of said piston is slidably guided, an .annular valve chamber formed between said block and liner having a valve reciprocable therein, passages within said valve block and liner controlled by the neck of said stem for admitting pressure uid into one end of said piston chamber to actuate said piston in one direction, passages leading from the interior of said liner and controlled by said valve for admitting pressure liuid into the other end of said piston chamber to actuate said piston in the other direction, an exhaust port controlled by said piston for exhausting both ends of said chamber, said valve comprising a restricted pressure area constantly subjected to the action of the pressure fluid for shifting and holding said ALBERT FEUCHT. 

